1. Technical Field
The present disclosure relates to a structure of leads within a via in a substrate, and more particularly to a structure of multiple coaxial leads within a single via in a substrate.
2. Description of Related Art
As the manufacturing process of semiconductors becomes more and more precise, in the future manufacturing process below 45 nm, the problem of severe impedance mismatch inevitably occurs when it intends to guide an ultra-thin lead with a width lower than 45 nm to pass through a via with an aperture larger than 1 μm and connect the ultra-thin lead to another ultra-thin lead, and thereby, it fails to achieve a high-speed signal transmission. However, if a plurality of leads is disposed in the via to solve the above problem, the problem of crosstalk among the plurality of leads turns to occur.
For example, U.S. Pat. No. 5,587,119 discloses a coaxial lead structure. FIGS. 1A to 1F are schematic cross-sectional views of a coaxial lead structure manufactured by a method provided in U.S. Pat. No. 5,587,119. First, referring to FIG. 1A, a substrate 102 is provided. Then, a first via 104 is disposed in the substrate 102, the substrate 102 has an upper surface 106 and a lower surface 108, and the first via 104 has a via wall surface 110, as shown in FIG. 1B. Next, referring to FIG. 1C, a surface metal layer 112 and a via wall metal layer 114 are formed, and then a second via 116 with the via wall metal layer 114 is obtained. Afterward, an insulating material 118 is filled in the second via 116, as shown in FIG. 1D. Then, as shown in FIG. 1E, a third via 120 is disposed in a center of the insulating material 118. Finally, as shown in FIG. 1F, metal leads 122 are filled in the third via 120, so that the via wall metal layer 114, the insulating material 118, and the central metal leads 122 constitute the coaxial lead structure 100. In the coaxial lead structure 100, the via wall metal layer 114 may be grounded, and as the central metal leads 122 are surrounded thereby, the metal leads 122 are under good electromagnetic shielding, thus eliminating the problem of crosstalk.
U.S. Pat. No. 5,421,083 also discloses a coaxial lead structure. FIG. 2 is a schematic cross-sectional view of a coaxial lead structure manufactured by a method provided in U.S. Pat. No. 5,421,083. The coaxial lead structure 200 includes a substrate 202, a first conductive layer 204, a second conductive layer 206, a first insulating layer 208, and a second insulating layer 210. In this patent, both the first conductive layer 204 and the second conductive layer 206 pass through a via simultaneously to transmit signals.
U.S. Pat. No. 6,943,452 further discloses a coaxial lead structure. FIG. 3 is a schematic cross-sectional view of a coaxial lead structure provided in U.S. Pat. No. 6,943,452. The coaxial lead structure 300 includes a cylindrical lead 304 capable of being placed in a conductive tube 306 and electrically connected to the conductive tube 306. The conductive tube 306 is disposed in a composite substrate 302, and surrounded by a plurality of grounding devices 308. However, the grounding devices 308 are not continuous from top to bottom.
U.S. Pat. No. 7,404,250 further discloses a coaxial lead structure. FIG. 4 is a schematic cross-sectional view of a coaxial lead structure provided in U.S. Pat. No. 7,404,250. The coaxial lead structure 400 includes a first lead 404, insulating layers 406 surrounding the first lead 404, and second leads 410 and conductive layers 408 surrounding the insulating layers 406. The conductive layers 408 are electrically connected to the first lead 404. Similar to U.S. Pat. No. 5,421,083, this patent provides a solution that both the first lead 404 and the second leads 410 pass through a via simultaneously to transmit signals.
In addition, U.S. Pat. No. 6,943,452 and ROC Patent No. I248330 respectively disclose a lead structure including a grounding device, so as to reduce the crosstalk among the leads. U.S. Pat. No. 7,129,567 discloses a solution of disposing a plurality of leads within a single via.
As the manufacturing process of semiconductors becomes increasingly precise, it is an inevitable trend to manufacture multiple coaxial leads within a single via in the future, which may increase the circuit density in a unit of area, and make the products thinner, lighter, shorter, and smaller. However, seen from the above, the prior art discloses the manufacturing of one coaxial lead in a single via or the manufacturing of a plurality of leads in a single via, and the problem of crosstalk still exists. Therefore, manufacturing a plurality of coaxial leads in a single via while avoiding the problem of crosstalk is needed urgently.